Update
using safe mode removed avast using downloaded avast clear utility , restarted, cleaned with ccleaner and did fresh install, all appears good now and uptodate! Thankyou!
suggestion
if default "ask" when to update is selected in settings, maybe, as a failsafe, if you click blue alert update now install, give a second dialog box from that with option to proceed with auto installation or option "download current avast removal tool and newversion.exe for manual removal and update" something like that might be useful
also if anyone like me on win7 starter a bit unsure about how to get into safe mode (to use clear.exe) perhaps a brief script to accompany exe, script on your site or links to microsoft site ... I found this bit of text very helpful:
Through System Configuration (msconfig)
1. To Start Windows 7 in Safe Mode
warning Warning
This will set Windows 7 to start into Safe Mode until you set it back to the normal boot mode in step 2 below.
A) Open the Start Menu, then type msconfig in the search box and press Enter.
B) If prompted by UAC, click on Yes.
C) Click on the Boot tab.
D) Select Windows 7 at the top, then check Safe boot and dot Minimal.
E) Click on OK and restart the computer.
F) The computer will now restart and start Windows 7 into Safe Mode.
2. To Start Windows 7 Back in Normal Mode
A) Open the Start Menu, then type msconfig in the search box and press Enter.
B) If prompted by UAC, click on Yes.
C) Click on the General tab.
D) Select (dot) Normal startup.
E) Click on the Boot tab, and check
F) Click on OK and restart the computer.